Well casing stop collar

ABSTRACT

A stop collar comprising an interrupted, circular band with opposed ends, a deformable knockdown buckle mounted on the exterior at one end of the band, and a drawplate extending from the opposite end of the band. The end of the band having the knockdown buckle includes an extension tongue slidably projecting through a window in the drawplate to engage the interior side of the opposite end of the band.

United States Patent Inventor James E. Harrison Weatheriord, Tex. Appl. No. 45,472 Filed June 11, 1970 Patented Oct. 19, 1971 Assignee Trojan, Inc.

Panama WELL CASING STOP COLLAR 4 Claims, 9 Drawing Figs.

US. Cl 287/52, 166/241 Int. Cl F16d 1/06 Field of Search 287/52 R, 52.03; 166/241 [56] References Cited UNITED STATES PATENTS 2,846,016 8/1958 Hanes 287/52.04 2,986,415 5/1961 Park 287/52R 3,147,029 9/1964 Hall, Sr 287/52 R Primary Examiner-David J. Williamowsky Assistant Examiner-Andrew V. Kundrat AnorneyScofield, Kokjer, Scofield & Lowe PATENTEDum 19 l97l SHEET 2 [IF 2 WI WEN I NVENTOR James Herr/.5027

WELL CASING STOP COLLAR BACKGROUND OF THE INVENTION In the field of oil well drilling and completion for production, various tools and appliances, such as centralizers, scratchers, solidifiers, baskets, and the like, have been developed for centering the casing within the well bore and for cleaning or otherwise scraping the walls of the bore to facilitate the placing of the cement column surrounding the casing and to assure a satisfactory bonding of the column to the wall of the well.

Devices known as stop collars have been developed which circumferentially grip the casing to confine the longitudinal movement of such appliances on the casing. A wide variety of means have been employed to fix stop collars upon the casing, ranging from welding to friction fits using bolt, setscrew, or wedging pin arrangements.

The mounting of such cementing equipment with conventional stop collars has taught that installation is time consuming during a period when speed of installation may be of crucial importance. There remains a need in this art for as top collar having superior tripping qualities and which can be easily and quickly installed on the well casing.

The primary object of this invention is to provide a stop collar which can be easily and positively installed on well casing in a surprisingly short period of time. The extremely fast installation is accomplished without the need for special installation tools be merely hammering or otherwise substantially flattening a knockdown buckle which projects from the exterior surface of the collar.

Another object of the invention is to provide a stop collar of the character described which is a complete device in itself, having no separate parts or members necessary to install the collar on well casing. This feature also cumulatively aids in the installation speed since there are no additional parts which might be mislaid, lost, or dropped.

An additional object of the invention is to provide a stop collar which, prior to installation, encircles the casing and can be easily slipped therealong. After installation, the collar has superior gripping qualities as if it was an integral part of the casing itself.

A further object of the invention is to provide a stop collar of the character described which is of durable and rugged construction, functioning trouble-free in an application where the collar may be subjected to radial or longitudinal stresses by the movement of the casing in the well bore.

Other and further objects of the invention together with features of novelty appurtenant thereto will appear in the course of the following description.

DESCRIPTION OF THE DRAWINGS In the accompanying drawings, which form a part of the specification and are to be read in conjunction therewith, and in which like reference numerals are employed to indicate like parts in the various views:

FIG. 1 is a perspective view showing a stop collar, constructed in accordance with a preferred embodiment of the invention, installed on a section of well casing to limit movement of a cementing tool;

FIG. 2 is a plan view of the stop collar illustrating the construction prior to installation;

FIG. 3 is an exterior view along line 3-3 of FIG. 2 in the direction of the arrows showing the tightening portion of the gripping assembly of the stop collar prior to installation;

Flg. 4 is an interior view along line 4-4 of FIG. 2 in the direction of the arrows showing the tightening portion of the gripping assembly of the stop collar prior to installation;

FIG. 5 is a sectional view along line 5-5 of FIG. 3 in the direction of the arrows;

FIG. 6 is a sectional view along line 6-6 of FIG. 3 in the direction of the arrows.

FIG. 7 is an exploded tion of the stop collar;

perspective view of the tightening por- FIG. 8 is an enlarged, exterior view similar to that of FIG. 3, but illustrating the tightening portion after installation as shown in FIG. 1; and

FIG. 9 is an enlarged, interior view, similar to that of FIG. 4, but illustrating the tightening portion after installation.

Referring first to FIG. 1, a stop collar 20 according to the invention is shown installed on the well casing 21 and is immovable thereon. The pipe appliance 22, shown as an example of a centering and cementing tool mounted on the casing 21 with the aid of a stop collar 20, is known as a solidifying centralizer. This device comprises upper and lower collars 22a and 22b which slidably encircle the casing 21 above and below the stop collar 20 and which are interconnected by arcuate ribs or blades 220. Free end, vertically disposed baffle members 22d are attached to the lower collar 22!: and project upwardly therefrom within the blades 220. So constructed, the appliance 22 can move upwardly on the casing 21 until the lower collar 22b contacts the stop collar 20 or downwardly until the upper collar 22a contacts thestop collar 20.

A more detailed structural and functional description of such an appliance is found in US. Pat. No. 3,237,696 of Jesse E. Hall, Sr., issued Mar. 1, 1966, entitled Well Wall Solidifying Centralizer. However, it is to be understood that the stop collar herein is not limited in application to the specific tool described, but may be used with a wide variety of other type equipment.

Turning now to the stop collar itself and particularly r'eferring to FIGS. 2 through 7, the collar basically comprises a circular band 200 which is discontinuous to provide two adjacent ends 20b and 200. One such end 20b, hereafter referred to as the tongue end 20b, has an integral extension tongue 20d projecting therefrom which it tucked under the opposite end 20c of the band to engage the inner peripheral or interior surface thereof.

As best viewed in FIG. 6, the band 20a itself is integrally formed with inwardly turned circumferential edges and a pair of spaced, inwardly pressed exterior grooves which provide parallel ribs on the interior or gripping surface of the band 200. On the outer peripheral or exterior surface of the band 20a, the grooves provide a central land and a pair of outside lands.

Attached to the ribs and continuous throughout a portion of the band 20a are corrugated-like wedging strips 23. The general purpose of the wedging strips 23 is to provide gripping means to prevent movement of the collar 20 when installed on the casing 21. A more detailed structural and functional description of the wedging strips 23 can be found in US. Pat. No. 3,147,029 of Jesse E. Hall Sr., entitled Stop Device for Use with Well Casing, issued Sept. l, 1964.

Mounted on the tongue end 20b of the band just behind the extension tongue 20d itself, is a knockdown buckle 24 which is in the from of a T-shape. For securely attaching the buckle 24 to the band 20a, I prefer to spotweld the arm portion 240 to the band, as indicated at 24b and arc-weld the leading edge of the arm portion 240, as indicated at 240, for additional strength. The arcuate leg 24d, away from the tongue end 20b, and is aligned with an elongate, open window 20e. The window 20a begins slightly behind the rearward edge of the arm portion 24a of the buckle and extends in length slightly longer than the overall length of the leg portion 24d of the buckle.

Fixed to the opposite end 20c of the band on the interior side thereof is a drawplate 25, as best viewed in FIGS. 4 and 7, In order to securely attach the drawplate 25 to the band 200, I prefer spot-welding at various points, as indicated at 25a, and arc-welding the rear edge, as indicated at 25b, to provide additional strength. The drawplate 25 has an elongate slot 250 of sufficient width to receive the extension tongue 20d from the tongue en ti 20b of the band. The slot 25c is of sufficient length to permit the tongue 20d to be disposed therein when the ends 20b and 200 of the band are drawn together as will later be described.

On the opposite end of the drawplate 25, which extends undemeath the tongue end 20b of the band, is a raised portion 25d registering with the window e. As best viewed in FIG. 7, the raised portion d has a central opening 25e therein aligned with a central opening 24e in the outer end of the leg 24d of the buckle. Received within the openings 25c and 24a is a rivet 26 securely fastening the outer end of the leg 24d to the drawplate 25. For additional strength, the outer edge of the leg 24d is preferably arc-welded to the drawplate 25, as indicated at 24].

For installing the stop collar 20 as previously described on the well casing 21, reference to FIGS. 8 and 9 is helpful and the following description is applicable.

The stop collar 20 is first slipped over a free end of the well casing 21 which is slightly smaller diameter than the stop collar 20 itself. Thus encircling the casing 21, the collar 20 is moved along the casing 21 to the point of installation. The actual installation of the collar 20 requires only the flattening of the knockdown buckle 24 with a hammer, sledge or the like until the collar 20 securely grips the casing 21 and is immovable thereon.

As the leg 24d of the knockdown buckle is flattened, the outer end thereof moves away from the tongue end 20b within the window 20e and thus pulls the drawplate 25 past the tongue end 20b. As the two ends 20b and 200 of the band are drawn closer together by this action, the tongue 20d slides deeper into the elongated slot 250 in the drawplate 25. Once the collar 20 securely grips the well casing 21, the installation is complete.

Thereafter, a suitable pipe tool can be buckled around the well casing 21 to be limited in movement thereon by the stop collar 20. In this connection, some tools are not segmented to permit their application after the stop collar 20 is installed. Rather, these tools are continuous and must be slipped over a free end of the well casing 21 just as the stop collar 20 itself must be so applied. In this case, it is necessary that the stop collar 20 of this invention be assembled between he collars of the tool during the assembly process of said tool and such would be the case for the solidifying centralizer described herein as an example.

Should the extension tongue 20d attached to the tongue end 20b of the band be omitted or positioned on the exterior rather than the interior side of the opposite end 200, the tongue end 20!: will tend to spring out away from the opposite end 200 and away from the casing 21 when the buckle 24 is flattened. Therefore, the purpose of the extension tongue 20d is to retain the tongue end 20b inclose proximity with the casing 21 and opposite end 20c of the band, thus insuring a substantially circular shape to the collar when installed.

Likewise, when the buckle 24 is substantially flattened, the drawplate 25 would tend to lift or spring away from the casing 21 and collar 20 but for its engagement with the interior side of the band 20a.

From the foregoing, it will be seen that this invention is one well adapted to attain all of the ends and objects hereinabove set forth, together with other advantages which are obvious and which are inherent to the structure.

It will be understood that certain features and subcombinations are of utility and may be employed without reference to other features and subcombinations. This is contemplated by and is within the scope of the claims.

As many possible embodiments may be made of the invention without departing from the scope thereof, it is to be understood that all matter herein set forth or shown in the accompanying drawings is to be interpreted as illustrative and not in a limiting sense.

Having thus described my invention, I claim:

1. A substantially annular stop collar adapted for installation on well casing, said collar comprising:

an interrupted, circular band providing first and second end portions,

said first end portion including an extension having an elongate aperture therethrough and slidably engaging the inner peripheral surface of said second end portion, said second end portion having a tongue extending through said aperture to slidably engage the inner peripheral surface of aid first end portion,

a deformable knockdown buckle attached to said second end portion to the rear of said tongue and arcuately projecting from the outer peripheral surface of said band, and

an elongate open window in said second end portion through which the rearmost end of said buckle is securely attached to said extension of said first end portion,

whereby said buckle can be substantially flattened to overlappingly draw together said first and second end portions and thus decrease the diameter of said band to cause same to grip the well casing.

2. The stop collar as in claim 1, said extension of said first end portion comprising a drawplate with one end thereof securely attached to the inner peripheral surface of said first end portion and with the opposite end thereof slidably engaging the inner peripheral surface of said second end portion and attached to said buckle,

said plate further including an elongate aperture extending into that portion of said plate attached to said first end portion in order to receive said tongue.

3. The stop collar as in claim 1, said extension having a raised portion which extends upwardly into said window and on which is securely fixed the reannost end of said buckle.

4. The stop collar as in claim 1, including corrugated-like wedging strips mounted on the inner peripheral surface of said band and continuous throughout a portion thereof to fixedly grip the well casing when said buckle is flattened so as to prevent movement of the collar on the casing. 

1. A substantially annular stop collar adapted for installation on well casing, said collar comprising: an interrupted, circular band providing first and second end portions, said first end portion including an extension having an elongate aperture therethrough and slidably engaging the inner peripheral surface of said second end portion, said second end portion having a tongue extending through said aperture to slidably engage the inner peripheral surface of aid first end portion, a deformable knockdown buckle attached to said second end portion to the rear of said tongue and arcuately projecting from the outer peripheral surface of said band, and an elongate, open window in said second end portion through which the rearmost end of said buckle is securely attached to said extension of said first end portion, whereby said buckle can be substantially flattened to overlappingly draw together said first and second end portions and thus decrease the diameter of said band to cause same to grip the well casing.
 2. The stop collar as in claim 1, said extension of said first end portion comprising a drawplate with one end thereof securely attached to the inner peripheral surface of said first end portion and with the opposite end thereof slidably engaging the inner peripheral surface of said second end portion and attached to said buckle, said plate further including an elongate aperture extending into that portion of said plate attached to said first end portion in order to receive said tongue.
 3. The stop collar as in claim 1, said extension having a raised portion which extends upwardly into said window and on which is securely fixed the rearmost end of said buckle.
 4. The stop collar as in claim 1, including corrugated-like wedging strips mounted on the inner peripheral surface of said band and continuous throughout a portion thereof to fixedly grip the well casing when said buckle is flattened so as to prevent movement of the collar on the casing. 